Flashcards in Exam 1.4: Principles of Radiography and Definitions Deck (56)
Physical properties of x-rays
Weightless and undetectable by human senses
What is notable about how x-rays travel?
Travel in straight lines
Cannot be focused on a convergent point
What allows x-rays to penetrate our tissues?
What is the difference between diagnostic and therapeutic radiation?
Therapeutic radiation causes a biological change
What is the tube made up inside the tube head?
What is inside the pyrex glass tube
Also, no air....vacuum tube
What is the negative electrode called
What is the function of the cathode?
It is the source of electrons
What is the cathode made of
Tungsten filament wound up inside a Molybdenum cup
Is the cathode stronger when it is thick or thin?
How does the cathode "release" electrons
The cathode has a very high melting point, when heated the electrons boil off
What is the name of the positive electrode?
What is the function of the anode
It is the target of the electrons released by cathode. It releases the radiation
What is the anode made from
copper with a tungsten target
What percent of the energy produced by the anode is immediately lost as heat?
What happens to the x-ray's energy when it scatters?
It is lowered
What does scatter cause in terms of image errors?
What is dangerous about scatter?
It is a source of patient exposure
What does it mean when the x-ray is attenuated?
It has been absorbed by the tissue
What values are important when trying to determine if an x-ray will be attenuated?
What is removed from the beam as it passes through, and is attenuated by tissue?
What is the result of attenuation on the image?
What are the two most attenuating tissues in the body?
Enamel and Cortical Bone
What results in complete attenuation of x-rays?
In a BW, what percent of x-rays pass through the tissue completely (transmitted) without any interaction at all?
If you want to increase the amount of x-rays in the beam (Cross sectional Density/Flux) what adjustment would you make to the machine?
What value dictates the penetrating power of the beam?
What is the primary safety feature of well designed x-ray systems?
Dead man switch
What is the inverse square law?
Intensity (I) = 1/d^2